Oracle sells Oracle Linux, a RedHat clone. ZFS on Linux (ZoL) isn't controlled by Oracle, it is a fork of OpenSolaris version of ZFS. The ZFS sold by Oracle on Solaris isn't the same product and doesn't support Linux. Oracle doesn't want to support it on Linux because it would fragment one of the remaining cash cow they got from Sun. And anyway, they probably can't support ZoL even if they wanted to without putting themselves into self induced legal gray water. Apparently, they intend to move Solaris into a rolling model like Windows 10, but focused on legacy. They can sell ZFS there without affecting their Linux operations. There is also a rumor of a deal with NetApp not to support ZFS on Linux. All combined, BTRFS is a better suited tech for them to support.